Assertion :- According to Lamarck, evolution of life forms had occured but driven by use and disuse of organs.
Use and disuse of organ leads to change at genetic level.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is a not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that according to Lamarck, evolution of life forms occurred due to the use and disuse of organs. This is true. Lamarck proposed that organisms adapt to their environment through the use of certain organs, which become more developed, while unused organs may diminish or disappear over generations.

2. **Understanding the Reason**:
- The reason claims that the use and disuse of organs lead to changes at the genetic level. This is false. Lamarck's theory does not involve genetic changes; rather, it focuses on the inheritance of acquired characteristics. Changes due to use and disuse occur in somatic cells and are not passed down genetically.

3. **Evaluating the Relationship**:
- Since the assertion is true and the reason is false, we conclude that the reason does not correctly explain the assertion.

4. **Conclusion**:
- The assertion is true, but the reason is false. Therefore, the correct answer is that the assertion is true, but the reason is not a correct explanation of the assertion.

### Final Answer:
- Assertion: True
- Reason: False